Heating of the interior of motor vehicles, for example, is known to be performed with the help of waste heat of a motor. For novel cars, however, as well as for ambient temperatures lying far below room temperature, it takes a rather long time after starting the motor in order to generate sufficient waste heat in order to heat the interior of the vehicle. Especially in case no additional heating sources are used, the time until the interior is sufficiently heated may be long and may thus have a negative influence with respect to comfort of the passengers.
In order to reduce the time required for heating the interior of a vehicle, additional heating sources are known for heating the interior of a vehicle during the warming-up phase.
A first class of heating devices requires an additional power source. For example, a heater driven by electrical energy such as from a battery or a generator or by using fuel as energy source may be provided. It may directly interact with the standard air conditioning system in use. Due to the big volume inside a vehicle, such as typically more than 3 m3, however, much energy is required to heat up the air inside the vehicle. As an exemplary value only, energy of approximately 78 kJ is required for increasing the temperature of 3 m3 of air by 20° C. The energy consumption is even more significantly raised by heat losses caused by heat transfer to a car body, for example in case energy is provided on a longer time scale (for example >>1 s).
As to a second class, latent-heat storage systems are known which are heated up during normal car operation such as by waste heat of the motor. They are designed to perform a solid-liquid phase transition and to release this energy during car warming-up phase at low ambient temperatures. These heat accumulators may particularly be used in case this energy storage system is stored at temperatures above the phase transition temperature and ambient temperatures below. These heat storage systems furthermore are mostly over-dimensioned in order to hold a sufficient heating capacity during off times.
Known from U.S. Pat. No. 4,660,629 is furthermore a continuously acting adsorption device and a process for its operation. Such an adsorption device may be used for heating the interior of a motor vehicle. It comprises a plurality of adsorption containers which are separated into heater adsorber zones and condenser evaporator zones. The zones are successively rotated through flow segments which form a passageway for heat carrier flows. The heater adsorption zones contain an adsorption substance from which an operating substance is extracted by adsorbing heat from a heat carrier flow and is again adsorbed by emitting heat to a further heat carrier flow in a closed system. The operating substance condenses and evaporates by means of a heat exchange with heat exchangers.
There is, however, still the need for heating devices which may decrease the time required for heating up the interior of a vehicle during warming-up phase and/or which may be easy and cost-saving to build and/or to operate.